From: Steven Rostedt rostedt@goodmis.org
[ Upstream commit c44a14f216f45d8bf1634b52854a699d7090f1e8 ]
Enforce that the address and the size of the memory used by the persistent ring buffer is page aligned. Also update the documentation to reflect this requirement.
Link: https://lore.kernel.org/all/CAHk-=whUOfVucfJRt7E0AH+GV41ELmS4wJqxHDnui6Giddf...
Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Mathieu Desnoyers mathieu.desnoyers@efficios.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Vincent Donnefort vdonnefort@google.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Mike Rapoport rppt@kernel.org Cc: Jann Horn jannh@google.com Link: https://lore.kernel.org/20250402144953.412882844@goodmis.org Suggested-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Sasha Levin sashal@kernel.org --- Documentation/admin-guide/kernel-parameters.txt | 2 ++ Documentation/trace/debugging.rst | 2 ++ kernel/trace/trace.c | 10 ++++++++++ 3 files changed, 14 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 3872bc6ec49d6..0a60a60cf7a7b 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6926,6 +6926,8 @@ This is just one of many ways that can clear memory. Make sure your system keeps the content of memory across reboots before relying on this option.
+ NB: Both the mapped address and size must be page aligned for the architecture. + See also Documentation/trace/debugging.rst
diff --git a/Documentation/trace/debugging.rst b/Documentation/trace/debugging.rst index 54fb16239d703..d54bc500af80b 100644 --- a/Documentation/trace/debugging.rst +++ b/Documentation/trace/debugging.rst @@ -136,6 +136,8 @@ kernel, so only the same kernel is guaranteed to work if the mapping is preserved. Switching to a different kernel version may find a different layout and mark the buffer as invalid.
+NB: Both the mapped address and size must be page aligned for the architecture. + Using trace_printk() in the boot instance ----------------------------------------- By default, the content of trace_printk() goes into the top level tracing diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 13f817afba4c2..2f72d05570d04 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10403,6 +10403,16 @@ __init static void enable_instances(void) }
if (start) { + /* Start and size must be page aligned */ + if (start & ~PAGE_MASK) { + pr_warn("Tracing: mapping start addr %pa is not page aligned\n", &start); + continue; + } + if (size & ~PAGE_MASK) { + pr_warn("Tracing: mapping size %pa is not page aligned\n", &size); + continue; + } + addr = map_pages(start, size); if (addr) { pr_info("Tracing: mapped boot instance %s at physical memory %pa of size 0x%lx\n",